In the macroscopic systems the continuous reservoir states play a passive role,
merely as a sink for the population of the initially prepared state. The reason is evident, there are no reverse \(R \rightarrow S\) 
transitions since the recurrence cycles periods are infinitely long. By contrast in nano-systems possessing reservoirs
with discrete dense spectra, the reservoir enters actively into the system dynamics.
The states of the reservoir with a dense discrete spectrum are periodically occupied in the direct \(S \rightarrow R\)  transitions and then
depleted in the reverse \(R \rightarrow S\)  transitions. Synchronicity of the reverse transitions leads to the double resonance phenomenon at the reservoir eigen-frequencies. These double resonances hold (and can be observed) even when the Loshmidt echo components are overlapped,
therefore the double resonances provide a convenient and powerful method for experimental studies of the ultra-fast energy redistribution processes [1]} - [2]}.
